Chitin is highly insoluble N-acetylated polymer of β-(1,4)-D-glucosamine. Chitosan is an acid-soluble deacetylated form of chitin. Chitin is commonly found in exoskeletons of marine invertebrates and cuticles of insects. Both chitin and chitosan are also present in the cell wall of most Zygomycetes as.
Chitosan can be obtained by deacetylating chitin prepared from crab or shrimp shell. However, this process fails to produce chitosan of uniform quality. Moreover, the composition of crab or shrimp shell is highly dependent upon seasonal and environmental factors. Therefore, it is difficult to obtain from crab or shrimp chitosan with consistent physio-chemical properties. Chitosan can also be obtained from a filamentous fungus of the family Mucoraceae. No chemical deacetylation is necessary in the process. As a result, the quality of fungal chitosan is more consistent.